Ewan Grant-Mackie – a 2006 New Zealand Science, Maths and Technology teacher fellow – compared DNA barcodes of swamphens from different countries to find out how these birds are related.
Pūkeko, takahē and moho
New Zealand swamphens, like the pūkeko, takahē and extinct moho, all belong to the Porphyrio genus. These types of birds are found all over the world, including Europe, Africa, Asia, Indonesia, the Philippines, Australia and throughout the Pacific Islands.
DNA barcoding is being used to unravel the evolutionary relationships between our native birds and their overseas relatives. This DNA approach can give us clues about where the New Zealand swamphens came from and how they got here.
The investigation
In 2006, Ewan Grant-Mackie – a New Zealand Science, Mathematics, and Technology Teacher Fellow, hosted by the Allan Wilson Centre and the University of Waikato – determined the DNA barcodes from North Island and South Island pūkeko, takahē, moho, Samoan swamphens, Solomon Island swamphens, Tongan swamphens and Australian swamphens.
Using museum samples
The moho sample and the Polynesian (Samoan, Solomon Island and Tongan) swamphen samples came from museum specimens. One of these birds had been collected in the 1920s!
Extracting DNA from museum samples requires special techniques.
For further information, see article: Extracting ancient DNA.
Barcoding the birds
A was created for each species by sequencing the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene.
Read more about DNA barcoding.
Find out about The ideal barcoding gene.
DNA barcodes support separate species
Scientists are not sure whether the extinct moho (also known as the North Island takahē) and the takahē are the same or separate species. Analysis of their barcodes indicates significant difference. This supports the view that they are separate species.
Some unexpected relationships
The DNA barcodes from pūkeko samples, however, unearthed some unexpected relationships. The North Island pūkeko barcodes were similar to those from Australian pūkeko, whereas the South Island pūkeko barcodes were similar to Polynesian pūkeko.
What might this mean for New Zealand birds?
Different barcodes for North and South Island pūkeko suggest that these birds have different evolutionary backgrounds, that is, they evolved in different places with different selection pressures.
The wandering pūkeko
The DNA barcodes suggest that North Island pūkeko may have been introduced from Australia. We know that birds either fly or are blown over from Australia because, from time to time, kookaburras show up here, whereas South Island pūkeko may have come from Polynesia. However, as this journey would be against the prevailing wind direction, it is unlikely that they made this journey under their own power.
There is at least one account that the Aotea canoe brought pūkeko, as well as the kākāriki, kurī, kiore and several plant species, when it made the trip to New Zealand about 1300 AD.
More research to do
This initial research into the DNA barcodes of pūkeko, takahē and moho raises many interesting questions. Researchers will need to investigate more DNA barcodes before they can make any claims about the origins of New Zealand’s native bird species.
Useful link
2015 research on gene sequences suggest that takahe have cousins in Africa and pukekos have Australian relations, read about this here.
